Public safety agencies, for example, emergency first responder organizations, such as police or fire departments, or public works organizations may use two way radios to communicate. Examples of two way radios include portable two-way radios, mobile radios, or other similar voice communication entities that communicate with one another via wired and/or wireless networks. Two way radio systems have a group message feature where a voice or data message sent from one radio is broadcast to multiple radios associated with a talk group. However there is currently no method for a receiving radio to know whether it missed a group message.
Consider an example where a supervisor sends an assignment via a talk group message to radios assigned to employees and associated with a talk group. If during the time the message is sent, one or more of receiving radio(s) assigned to the talk group are, for example, out of a coverage area where the radios operate, working on a different frequency, or powered off (in other words, one or more of the radios assigned to the talk group is incapable of receiving the talk group message at a particular time), those receiving radios will not receive the talk group message. Later, when each of those receiving radios becomes capable of receiving the talk group message by, for example, returning to the coverage area, tuning in to the correct frequency or being powered on, there is no mechanism for either the sending radio or the receiving radio that was previously incapable of receiving the talk group message to determine that the receiving radio failed to receive the talk group message(s) that were sent during the period when that radio was incapable of receiving the talk group message.
In addition, there are times when a sending radio may want to resend a group message. Consider an example where the sending radio receives an indication from one or more receiving radios that those receiving radios failed to receive a talk group message that was otherwise successfully sent to the rest of the talk group. The sending radio may choose to resend the message to the talk group rather than responding individually to each receiving radio from which an indication was received. When the sending radio resends the talk group message, there is also no way for the receiving radios, including those receiving radios that successfully received the original talk group message, to determine whether the resent talk group message is a duplicate message or a new message.
Accordingly, there is a need for an improved method and apparatus for enabling a receiving radio to automatically retrieve a missed talk group message and/or identify a duplicate talk group message.
Skilled artisans will appreciate that elements in the figures are illustrated for simplicity and clarity and have not necessarily been drawn to scale. For example, the dimensions of some of the elements in the figures may be exaggerated relative to other elements to help to improve understanding of embodiments of the present invention.
The apparatus and method components have been represented where appropriate by conventional symbols in the drawings, showing only those specific details that are pertinent to understanding the embodiments of the present invention so as not to obscure the disclosure with details that will be readily apparent to those of ordinary skill in the art having the benefit of the description herein.